Aetificial limb



Aug. 7, 1951 Filed Aug. 2l,` 1948 C. A. RENFRO ARTIFICIAL LIMB KNEE JOINT 2 Sheets-Sheet 1 JNVENTOR. CLARENCE A. RENFRO Aug. 7, 1951 c. A. -RENFRO ARTIFICIAL LIMB KNEE JOINT 2 Sheets-Sheet 2 Fiwled Aug. 2l, 1948 INVENTOR. CLARENCE A: REN/:R0 1%/ 76 AGE/VT Patented Aug. 7, 1951 UNITED STATES PATENT OFFICE l Claim.

My invention relates to an artificial limb knee joint, and the objects of my invention are:

First, to provide a joint of this class in which substantially automatic spring-loaded forward return of the shin joint of an artificial limb is accomplished during the walking motion of the wearer, which forward motion may be regulated according to the speed required by the wearer directly proportioned to his stride;

Second, to provide an articial limb knee joint in which spring-loaded forward motion of the `shin joint is modified by an adjustable friction collar, which directly regulates the speed of return of said shin joint, whereby shock of abutment of the shin joint at its forward limit of travel is minimized;

Third, to provide an artificial limb knee joint of this class which is very sturdy and is so constructed that the limb hinge bearing is provided with a continuous flexible bushing extending from one side of the upper limb member to the opposite side thereof, greatly increasing stability of the joint, and long-wearing characteristics, in addition to dampening shock stresses transferred to the limb hinge bearing from the foot of the artificial limb;

Fourth, to provide an artificial limb knee joint of this class having automatic spring-loaded means for the forward return of the lower limb when walking, which automatically tends to retract the lower limb when the same is disposed at substantially right angles to the upper limb in sitting position, whereby thelower limb does not tend to move forward from a natural position when the wearer is sitting clown;

Fifth, to provide an artificial limb knee joint of this class which is particularly adapted for use in connection with the stump of a limb amputated directly at the knee joint;

Sixth, to provide an artificial limb knee joint of this class which is very light and compact in proportion to its function;

Seventh, to provide an artificial limb knee joint of this class which is particularly adapted for use by persons desiring an end bearing socket fitting; and

Eighth, to provide an artificial limb knee joint of this class which is very simple and economical of construction, efficient in operation, and which will not readily deteriorate or get out of order.

With these and other objects in view, as will appear hereinafter, my invention consists of certain novel features of construction, combination and arrangement of parts and portions, as

will be hereinafter described in detail, and particularly set forth in the appended claim, reference being had to the accompanying drawings and to the characters of reference thereon, forming a part of this applicatiomin which:

Fig. l is a side elevational view of an artificial limb, showing my articial limb knee joint in connection therewith; Fig. 2 is a rear view similar to Fig. l, showing the artificial limb fragmentarily; Fig. 3 is a side elevational view of the knee joint operating mechanism, showing portions brokenaway and in section to amplify the illustration; Fig. 4 is an enlarged rear elevational view of the operating mechanism shown in Fig. 3 of the drawings; Fig. 5 is a sectional view taken from the line 5-5 of Fig. 4, showing parts and portions in elevation to facilitate the illustration; Fig. 6 is a plan sectional View, taken from the line E-6 of Fig. 2, showing the structure on an enlarged scale; Fig. 7 is an enlarged fragmentary sectional view taken from the line 1*-1 of Fig. 3; and Fig. 8 is an enlarged fragmentary sectional View taken from the line 8-8 of Fig. 1.

Similar characters of reference refer to similar parts and portions throughout the several views of the drawings.

The upper limb member |,limb shin member 2, limb hinge bearing straps 3 and 4, bearing bolts 5 and li, leather bushing 1, brackets 8 and 9, plate I0, links II and I2, spring I3, friction collar I4, friction adjusting screw I5, screw I6, bolts Il, I8 and ISI, and the bearings 20, 2l and 22 constitute the principal parts and portions of my artificial limb knee joint.

The upper limb member I is preferably a socket fitting for amputees having either end bearing stubs or those in which part of the weight bearing is around the upper edge of the upper limb member I. Hinged to the upper limb member I by means of the limb hinge bearing straps 3 and 4 and the bearing bolts 5 and 6 is the limb shin member 2. The limb hinge bearing straps 3 and 4 are xed to opposite sides of the limb shin member 2 and are recessed therein flush with the outer surface thereof. These limb hinge bearings 3 and 4 are substantially identical; therefore. the hinge bearing strap 3 will be hereinafter described. This hinge bearing strap 3 is the upper end of the limb hinge bearing strap 4, and is provided with an internal bore 6b, screwthreaded on the externally screw-threaded stub 5b of the bolt 5. Thus, the outer surface portions of the bolts 5 and 6 form a smooth continuous bearing for the leather bushing 'I, which .is a hollow-cylindrical bushing of iiexible character, adapted to absorb certain shocks transmitted by the bolts 5 and 6 from the lower shin member 2 during walking of the wearer on my artificial limb knee joint.

As shown in Figs. 2, 3 and 4, the bracket 8 is xed to the upper limb member I by pins 8a, and this bracket 8 is provided with a clevis portion 8b in which the normally upper end of the link II is pivotally mounted by means of the bolt I9. The normally lower end of the link II is pivotally connected with the link I2 by'means of the bolt I'I, and the normally lower end of the link I2 is pivotally connected to the bracket 9 by means of the bolt I8, all as shown best in Fig. 3 of the drawings. The bracket 9 is connected to the frontal portion of the limb shin 2 by means of the plate I engaging the outer side thereof, with which the screws Ilia are connected, and extending into screw-threaded relationship with the bracket il,Y forming a rigid anchor for the bolt i3, on which the link I2 is pivotally mounted.

The bearings 20, 2l and 22 are ball bearings, shown best in detail in Fig. of the drawings, which greatly reduce frictional loss in the pivotal operation of the links lI I and I2, all as shown best in Fig. 3 of the drawings, it being noted that the bearing is positioned on the bolt Il, the bearing -2I on the bolt I8, vand the bearing 22 on the bolt I9. y

The friction collar I4 is provided with a hollow cylindrical portion Illa, whichfsnugly iits a laterally-extending cylindrical trunnion I2aof the link I2, and this friction collar Ill is provided with slotted lugs I4b,.relieved to the central bore of the collar I4, as shown best in Fig. 3 of the drawings. The friction adjusting screw I5 passes through the lugs Illb and tends to clamp the cylindrical portion Illa of the collar I4 around the trunnion portion IBG. of the link I2 for regulating the frictional drag of the link I2 relatively to the link II, it being noted that the friction adjusting collar is provided with the lugs I4c and I4d engaging opposite sides of the link II, while the screw I5 is screw-threaded in the link II and holds the friction adjusting collar rigidly connected to the link II. It will be noted that the friction adjusting screw I5 is screw-threaded in the individual lug llie and the opposite lug of the collar I4 is free longitudinally of the screw I5, permitting the lugs Ilib and Me tobe forced toward each other for tightening the collar I4 around the trunnion I2a.

The helical spring I3 is connected at its one end I3a to a boss I la by a screw I Ib. The helical body I3c of this spring I3 Ais wound around the extending trunnion I2b of the link I2, and the opposite end I3b of the spring i3' from the end I3a engages the normally upper side of the link I2, as shown best in Fig. 3 ofI the drawings. The link Il, intermediate its ends, is provided with a bumper plate I Ic, engageable with a bumper pad la at the rear of the upper limb member I, at lits lower extremity. This bumper `pad la acts as a forward stop for the pivotal movement of the limb shin member 2 relatively to the upper limb member I.

The operation of my articial limb knee joint is substantially as follows: When the wearer of my artificial limb knee joint is walking, the spring I3 tends to force the bolt I'I, connecting the links II and l2, toward the frontal portion of the knee joint, which acts about the axis of the bolts 5 and 6, tending to force the limb shin member 2 forwardly. Thus, each time a step has been completed and the artificial limb is raised, the spring I3 pivots the lower shin member 2 forwardly for the beginning of another step. The forward speed of the limb shin member 2 forwardly when urged by the spring I3 is regulated by the friction collar I4, frictionally adjustable on the trunnion I2a of the link l2 by means of the friction adjusting screw I5. Tightening or loosening of this friction adjusting screw I5 results in slower or faster forward motion of the limb shin member 2 forwardly, as desired. Thus, the friction adjusting screw permits the regulation of the forward movement of the limb shin member 2, in accordance with the stride of the wearer, so that a direct synchronism with the normal limb of the wearer may be made, so that the movementsof the articial limb closely simulate the normal limb.

When the wearer of my artificial limb knee joint sits down, the bracket 8 is forced into the dash line position as shown in Fig. 3 of the drawings, wherein the bolt I 9 passes over center of the axis of the bolts 5 and E, causing the spring I3 to create backward pivotal tension of the limb shin member 2, tending to retract the sameinstead of forcing the same forwardly, which is nor' mal to the standing position, as shown bythe solid lines, in Fig. 3 of the drawings.

It will be noted that the bumper pad Ia. engaging the bumper plate IIc provides a cushion stop for the limb shin member 2 when pivoted forwardlyv by means of the spring I3 about the axis of the bolts 5 and 6. The frictional operation of the friction collar I4 on the trunnion I2a ofthe link I2V provides for deceleration of thelimb shinmember 2 in its forward swinging motion about the axis of the bolts 5 and 6, as the plate IIc of the link II approaches the pad Ia in connection with the upper limb member I. This deceleration accompanies progressive relaxation of the spring I3, the tension of which lessens slightly proportionately progressive to the forward pivotal movement of the limb shin member` 2 about the axis of the bolts 5 and 6. As hereinbefore described, the leather bushing 1 provides a flexible, yieldable bearing for the bolts 5 and 6, on which the limb hinge bearing straps 3 and 4 are mounted, it being noted that the straps 3 and 4 pivot on the bolts 5 and 6, respectively,

and that the leather bushing 'I does not bear any frictional load or wear occasioned by the pivotal movement of the limb shin member 2 relatively to the upper limb member I.

Though I have shown and described a particular construction, combination and arrangement of parts and portions, I do not wish to be limited to this particular construction, combination and arrangement, but desire to include in the scope of my invention the construction, combination and arrangement substantially as set forth in the appended claim. Y

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is: In an artificial limb knee joint of the class described, an upper limb member, a lower limb member, a bracket xed to said upper limb member, a bracket xed to said lower limb member, a linklpivoted to the bracket in connection with said upper limb member, a second link pivoted in connection with the bracket secured to said lower limb member, the opposite ends of said links from said brackets pivotally connected together, and spring means tending to pivot the lower limb member forwardly relatively to the upper limb member. said spring means acting around the axis of the pivotal connection of said links, an adjustable collar, said link pivotally connected to the bracket secured to the lower limb member said collar being split at one side and a friction x5 adjusting screw arranged to tighten said collar on said trunnion, whereby action of said spring may be modiiied, permitting'sald lower limb member to pivot relatively to said upper limb member urged by said spring at a slower or faster rate, as desired.

CLARENCE A. RENFRO.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date 41,033 Vaughan Dec. 22, 1863 42.799 Shepard May 17, 1864 '157,287 Duggan Apr. 12, 1904 1,072,369 Spahn Sept. 2, 1913 1,928,394 Schroder Sept. 26, 1933 

